In the present day, beamline ion implanters employ multiple components to direct an ion beam from an ion source to a substrate. In order to properly treat a substrate, the ion beam may be accelerated to a target ion energy, and may have its trajectory and shape manipulated by various beamline components to produce a set of target characteristics of the ion beam at the substrate. In many types of ion implanters, including medium energy and high energy ion implanters, an acceleration column(s) may be employed to accelerate or decelerate an ion beam in order to generate a target beam energy. A given acceleration column may include many electrodes arranged in electrical series fashion to accelerate an ion beam. For example, an acceleration column may include multiple electrodes having apertures to conduct the ion beam and arranged to increase a beam energy by applying a series of different potentials to the different electrodes. In this manner, the ion beam is accelerated according to the different potentials applied to the electrodes. In some examples, the potential applied to different electrodes may be increased from a first electrode in an acceleration column to a last electrode in an acceleration column, where the ion beam enters the acceleration column having a relatively lower energy and exits having a relatively higher energy.
Because in beamline ion implanters often just a target ion species, such as a dopant species, is to be implanted into a substrate, ensuring the ion beam has minimal contact with components used to manipulate the ion beam between ion source and substrate may be useful. In the case of electrodes used in an acceleration column, at least some ions in the ion beam may inadvertently strike an electrode, causing sputtering of material from the electrode. This sputtering may result in contaminant species from the electrode being generated where the contaminant species may be ionized and conducted to the substrate in addition to the target species. Known electrodes in acceleration columns, for example, may be constructed using titanium or other electrically conductive material. Titanium provides a machinable and relatively refractory metal (melting point 1668° C.), has a low coefficient of thermal expansion, making titanium generally suitable for an electrode. When an ion beam is conducted through an acceleration column containing titanium electrodes, titanium may be inadvertently sputtered by the ion beam, resulting in titanium contamination in a substrate, such as a silicon wafer. This contamination may be problematic for performance of a semiconductor device being fabricated from the substrate. While constructing an electrode in an accelerator column from another material may be possible, less damaging to semiconductor properties, other materials may have less desirable properties, such as higher thermal coefficient of expansion, or lower elastic modulus.
With respect to these and other considerations the present disclosure is provided.